Synchronization of tool acceleration vs time data and driller depth vs time data

Abstract

Processes and systems for synchronizing driller depth data as a function of time with downhole tool acceleration data as a function of time. In some embodiments, the process can include determining one or more in slips conditions for a drill pipe; determining one or more in slips conditions for a downhole tool; interpolating the in slips status indicators on to a common time grid; determining one or more shifts for which an allowed minimum overlapping time period between the acceleration data and the driller depth data is not less than an allowed minimum overlapping time period; determining a correlation coefficient between the interpolated in slips status indicators for each of the one or more shifts; determining a maximum correlation coefficient and a time shift associated with the maximum correlation; and synchronizing the acceleration data and the driller depth data.

What is claimed is: 
     
         1 . A process for synchronizing driller depth data as a function of time with downhole tool acceleration data as a function of time, the process comprising:
 drilling a borehole with a drill string comprising a drill pipe and a downhole tool into a subterranean formation;   acquiring driller depth data as a function of time while the borehole is drilled with the drill string or while the drill string is retrieved from the borehole after drilling the borehole;   time stamping the acquired driller depth data;   acquiring acceleration data imparted on the downhole tool with one or more sensors;   time stamping the acquired acceleration data;   determining one or more in slips conditions for a drill pipe by generating one or more driller depth status indicators as a function of time from driller depth data taken that indicate the one or more in slips conditions for the drill pipe;   determining one or more in slips conditions for a downhole tool by generating one or more acceleration status indicators as a function of time from downhole tool acceleration data taken from the downhole tool that indicate the one or more in slips conditions for the downhole tool;   establishing a common time grid for the acceleration data and the driller depth data, the common time grid overlapping both the acceleration data and the driller depth data with a sampling rate determined by a maximum of a median time distance between adjacent time samples in an acceleration data time record and a median time distance between adjacent samples in a driller depth data time record, such that the sampling rate is snapped to the closest multiple of a second or a whole fraction of a second in the time grid;   interpolating the in slips status indicators on to the common time grid;   selecting an allowed minimum overlapping time period for the acceleration data and the driller depth data;   determining one or more shifts for which an overlapping time period between the acceleration data and the driller depth data is not less than the allowed minimum overlapping time period;   determining a correlation coefficient between the interpolated in slips status indicators for each of the one or more shifts;   determining a maximum correlation coefficient and a time shift associated with the maximum correlation; and   synchronizing the acceleration data and the driller depth data using the time shift associated with the maximum correlation,   wherein the one or more in slips conditions for the drill pipe are determined from the driller depth data after the drilling is completed.   
     
     
         2 . The process of  claim 1 , wherein synchronizing the acceleration data and the driller depth data comprises shifting the acceleration data utilizing the time shift associated with the maximum correlation coefficient. 
     
     
         3 . The process of  claim 1 , wherein synchronizing the acceleration data and the driller depth data comprises shifting the driller depth data utilizing the time shift associated with the maximum correlation coefficient. 
     
     
         4 . The process of  claim 1 , wherein the one or more driller depth status indicators comprise a driller depth binary indicator having a value of zero when the driller depth is unchanging and one when the driller depth is changing. 
     
     
         5 . The process of  claim 4 , wherein the driller depth binary indicator has a value of zero when the driller depth data is greater than zero but less than a first threshold value and has a value of one when the driller depth data is greater than the first threshold value. 
     
     
         6 . The process of  claim 1 , wherein the one or more acceleration status indicators comprise an acceleration binary indicator having a value of zero when the acceleration data is unchanging and one when the acceleration data is changing. 
     
     
         7 . The process of  claim 6 , wherein the acceleration binary indicator has a value of zero when the acceleration data is greater than zero but less than a second threshold value and has a value of one when the acceleration data is greater than the second threshold value. 
     
     
         8 . A system for synchronizing driller depth data as a function of time with downhole tool acceleration data as a function of time, comprising:
 a drill rig system comprising a drill string comprising a drill pipe and a downhole tool;   drill rig system instructions that when executed by the synchronization controller cause the synchronization controller to:
 drill a borehole with the drill string into a subterranean formation; 
 acquire driller depth data as a function of time while the borehole is drilled with the drill string or while the drill string is retrieved from the borehole after drilling the borehole; 
 time stamping the acquired driller depth data; 
 acquiring acceleration data imparted on the downhole tool with one or more sensors; 
 time stamping the acquired acceleration data; 
   a synchronization controller; and   synchronization controller instructions that when executed by the synchronization controller cause the synchronization controller to:
 determine one or more in slips conditions for a drill pipe by generating one or more driller depth status indicators as a function of time from driller depth data taken that indicate the one or more in slips conditions for the drill pipe; 
 determine one or more in slips conditions for a downhole tool by generating one or more acceleration status indicators as a function of time from downhole tool acceleration data taken from the downhole tool that indicate the one or more in slips conditions for the downhole tool; 
 establish a common time grid for the acceleration data and the driller depth data, the common time grid overlapping both the acceleration data and the driller depth data with a sampling rate determined by a maximum of a median time distance between adjacent time samples in an acceleration data time record and a median time distance between adjacent samples in a driller depth data time record, such that the sampling rate is snapped to the closest multiple of a second or a whole fraction of a second in the time grid; 
 interpolate the in slips status indicators on to the common time grid; 
 select an allowed minimum overlapping time period for the acceleration data and the driller depth data; 
 determine one or more shifts for which an overlapping time period between the acceleration data and the driller depth data is not less than the allowed minimum overlapping time period; 
 determine a correlation coefficient between the interpolated in slips status indicators for each of the one or more shifts; 
 determine a maximum correlation coefficient and a time shift associated with the maximum correlation; and 
 synchronize the acceleration data and the driller depth data using the time shift associated with the maximum correlation. 
   
     
     
         9 . The system of  claim 8 , wherein the synchronization controller instructions, when executed by the synchronization controller, cause the synchronization controller to synchronize the acceleration data and the driller depth data by shifting the acceleration data utilizing the time shift associated with the maximum correlation coefficient. 
     
     
         10 . The system of  claim 8 , wherein the synchronization controller instructions, when executed by the synchronization controller, cause the synchronization controller to synchronize the acceleration data and the driller depth data by shifting the driller depth data utilizing the time shift associated with the maximum correlation coefficient. 
     
     
         11 . The system of  claim 8 , wherein the one or more driller depth status indicators comprise a driller depth binary indicator having a value of zero when the driller depth is unchanging and one when the driller depth is changing. 
     
     
         12 . The system of  claim 11 , wherein the driller depth binary indicator has a value of zero when the driller depth data is greater than zero but less than a first threshold value and has a value of one when the driller depth data is greater than the first threshold value. 
     
     
         13 . The system of  claim 9 , wherein the one or more acceleration status indicators comprise an acceleration binary indicator having a value of zero when the acceleration data is unchanging and one when the acceleration data is changing. 
     
     
         14 . The system of  claim 13 , wherein the acceleration binary indicator has a value of zero when the acceleration data is greater than zero but less than a second threshold value and has a value of one when the acceleration data is greater than the second threshold value. 
     
     
         15 . A process for synchronizing driller depth data as a function of time with downhole tool acceleration data as a function of time, the process comprising:
 drilling a borehole with a drill string comprising a drill pipe and a downhole tool into a subterranean formation;   acquiring driller depth data as a function of time while the borehole is drilled with the drill string or while the drill string is retrieved from the borehole after drilling the borehole;   time stamping the acquired driller depth data;   acquiring acceleration data imparted on the downhole tool with one or more sensors;   time stamping the acquired acceleration data;   determining one or more in slips conditions for the drill pipe by generating one or more driller depth status indicators as a function of time from the driller depth data that indicate the one or more in slips conditions for the drill pipe;   determining one or more in slips conditions for the downhole tool by generating one or more acceleration status indicators as a function of time from the acceleration data that indicate the one or more in slips conditions for the downhole tool;   establishing a common time grid for the acceleration data and the driller depth data, the common time grid overlapping both the acceleration data and the driller depth data with a sampling rate determined by a maximum of a median time distance between adjacent time samples in an acceleration data time record and a median time distance between adjacent samples in a driller depth data time record, such that the sampling rate is snapped to the closest multiple of a second or a whole fraction of a second in the time grid;   interpolating the in slips status indicators on to the common time grid;   selecting an allowed minimum overlapping time period for the acceleration data and the driller depth data;   determining one or more shifts for which an overlapping time period between the acceleration data and the driller depth data is not less than the allowed minimum overlapping time period;   determining a correlation coefficient between the interpolated in slips status indicators for each of the one or more shifts;   determining a maximum correlation coefficient and a time shift associated with the maximum correlation; and   synchronizing the acceleration data and the driller depth data using the time shift associated with the maximum correlation.   
     
     
         16 . The process of  claim 15 , wherein the one or more driller depth status indicators comprise a driller depth binary indicator having a value of zero when the driller depth is unchanging and one when the driller depth is changing. 
     
     
         17 . The process of  claim 16 , wherein the driller depth binary indicator has a value of zero when the driller depth data is greater than zero but less than a first threshold value and has a value of one when the driller depth data is greater than the first threshold value. 
     
     
         18 . The process of  claim 15 , wherein the one or more acceleration status indicators comprise an acceleration binary indicator having a value of zero when the acceleration data is unchanging and one when the acceleration data is changing. 
     
     
         19 . The process of  claim 18 , wherein the acceleration binary indicator has a value of zero when the acceleration data is greater than zero but less than a second threshold value and has a value of one when the acceleration data is greater than the second threshold value.